Abstract:

Methods and wireless communication device for associating UWB (Ultra Wide
Band) WPAN devices through the processing of ranging information. Ranging
information represents the distance between a device and another device.
Devices can automatically determine whether association has occurred via
evaluation of, e.g., changes in distance, velocity and/or acceleration of
devices, optionally in conjunction with a user-gated technique. The
association between two wireless devices is carried out automatically
when the distance between them is below a certain threshold. In a
different embodiment, said distance information is used together with
user-gated information to take a decision on associate or not associate
two devices close to each other. Said user-gated information may be a
confirmation given by the user to associate, e.g. through a button, etc.

Claims:

1. A wireless communication device comprising:a transceiver capable of
transmitting and receiving a signal useable to obtain ranging information
between said transceiver and another device; anda processor capable of
processing said ranging information toautomatically determine whether
said wireless communication device has become associated with said
another device.

2. The device of claim 1, wherein said transceiver and said processor
operate to obtain said ranging information by: (a) exchanging ranging
messages between said transceiver and said another device, (b) solving
for a propagation delay between said transceiver and said another device
based upon transmission times and reception times of said ranging
messages and (c) determining said ranging information based on said
propagation delay.

3. The device of claim 1, wherein the ranging information is a distance
between said transceiver and said other device.

4. The device of claim 1, wherein said processor determines that said
device is associated with said another device when at least one first
condition occurs based on said ranging information obtained during a
measurement period.

5. The device of claim 4, wherein said at least one condition is that a
distance, between said devices, has closed by a predetermined amount
during the measurement period.

6. The device of claim 4, wherein said at least one condition is that a
velocity, between said devices, goes from zero to a positive value and
then back to zero during the measurement period.

7. The device of claim 4, wherein said at least one condition is that an
acceleration, between said devices, is first positive and then negative
during the measurement period.

8. The device of claim 1, wherein user feedback is provided when said
processor determines that said wireless communication devices has become
associated with said another device.

9. The device of claim 8, wherein user feedback is also provided upon
disassociation.

10. The device of claim 4, wherein said processor subsequently determines
that said wireless communication device has become disassociated with
said another device based upon at least one disassociation condition,
which is different than said at least one condition that said processor
uses to determine association.

11. A method for wireless communication comprising the steps
of:transmitting and receiving a signal useable to obtain ranging
information between said wireless communication device and another
device; and processing said ranging information to automatically
determine whether said wireless communication device has become
associated with said another device.

12. The method of claim 11, wherein said step of obtaining ranging
information further comprises the steps of: (a) exchanging ranging
messages between said transceiver and said another device, (b) solving
for a propagation delay between said transceiver and said another device
based upon transmission times and reception times of said ranging
messages and (c) determining said ranging information based on said
propagation delay.

13. The method of claim 11, wherein the ranging information is a distance
between said transceiver and said other device.

14. The method of claim 11, wherein said processor determines that said
device is associated with said another device when at least one first
condition occurs based on said ranging information obtained during a
measurement period.

15. The method of claim 14, wherein said at least one condition is that a
distance, between said devices, has closed by a predetermined amount
during the measurement period.

16. The method of claim 14, wherein said at least one condition is that a
velocity, between said devices, goes from zero to a positive value and
then back to zero during the measurement period.

17. The method of claim 14, wherein said at least one condition is that an
acceleration, between said devices, is first positive and then negative
during the measurement period.

18. The method of claim 11, further comprising the step of: providing user
feedback when said processor determines that said wireless communication
devices has become associated with said another device.

19. The method of claim 18, wherein the step of providing user feedback
further comprises the step of: providing said user feedback upon
disassociation.

20. The method of claim 14, wherein said processor subsequently determines
that said wireless communication device has become disassociated with
said another device based upon at least one disassociation condition,
which is association.

21. A wireless communication device comprising:a transceiver capable of
transmitting and receiving a signal useable to obtain ranging information
between said transceiver and another device; anda processor capable of
processing said ranging information together with at least one user-gated
authorization technique to determine whether said wireless communication
device has become associated with said another device.

22. The wireless communication device of claim 1, wherein said a processor
automatically determines that said wireless communication device has
become associated with said another device when said wireless
communication device is within one foot of said another device.

23. The wireless communication device of claim 22, wherein said processor
automatically determines that said wireless communication device has
become associated with said another device when said wireless
communication device is within 30 cm of said another device.

24. The method of claim 11 further comprising the step of: automatically
determining that said wireless communication device has become associated
with said another device when said wireless communication device is
within one foot of said another device.

25. The method of claim 24, further comprising the step of: automatically
determining that said wireless communication device has become associated
with said another device when said wireless communication device is
within 30 cm of said another device.

Description:

[0001]The present invention relates generally to Personal Area Network
(PAN) devices using Ultra Wideband (UWB) and, more particularly, to
systems and methods used by these devices to associate with a Piconet
Controller (PNC) using a ranging method, for example, a digital camera to
a printer.

[0002]Technologies associated with the communication of information have
evolved rapidly over the last several decades. For example, over the last
two decades wireless communication technologies have transitioned from
providing products that were originally viewed as novelty items to
providing products which are the fundamental means for mobile
communications. Perhaps the most influential of these wireless
technologies were cellular telephone systems and products. Cellular
technologies emerged to provide a mobile extension to existing wireline
communication systems, providing users with ubiquitous coverage using
traditional circuit-switched radio paths. More recently, however,
wireless communication technologies have begun to replace wireline
connections in almost every area of communications. Wireless local area
networks (WLANs) are rapidly becoming a popular alternative to the
conventional wired networks in homes, offices and public places (e.g.,
cafes, food chain restaurants, airports, aircrafts, etc.). Since the
advent of UWB (Ultra Wideband), the opportunities for wireless
communications in more areas of daily life are now expanded.

[0003]Wireless Personal Area Networks (WPANs) using UWB technology will
provide high-speed digital connections between PCs and digital
peripherals, such as flash memory cards and personal digital assistants
(PDAs), or between printers and digital cameras. In order to initiate
communication some form of association between the devices will first
occur. In the case of wired connectivity, the devices that are to be
associated with one another are physically plugged together with, for
example, either a UWB or 1394 cable, and the correct association between
devices is guaranteed. There is currently no simple equivalent to the
wire and plug paradigm that can be employed for a wireless system. Since
multiple, UWB capable devices may reside in, for example, the same room,
it would be useful for the devices themselves to recognize when an
association is intended.

[0004]Some solutions for providing associations in UWB WPAN devices have
been contemplated, however these solutions involve at least some user
interaction. One example involves providing each UWB device with a
printed card having a serial number. This serial number is entered into a
PC (for example) that the user wishes to be able to associate with the
UWB device and then, when the UWB device gets in range of the PC, a
YES/NO dialog box is displayed for confirmation of the association Some
drawbacks to this solution are that the serial number may become lost, or
it may become inconvenient for this dialog box to pop up each time that
an allowed UWB device gets within range. Furthermore, portable devices
may not have a suitable display to allow dialog box style interaction. A
second technique involves providing both the PNC and UWB device with
"associate now" buttons that are pressed simultaneously to establish an
association. This solution suffers from the potential for accidental
cross connections to occur in a densely populated area and from
awkwardness in trying to get a user to simultaneously press two buttons
on different devices. Yet another possible solution is to use an
infra-red transmission to initiate the request for association and
transfer other information as required. Some drawbacks to this solution
are the extra expense of the IR transceivers, the need for a button to be
pressed to initiate the IR association request, and the possibility that
user intervention for admission of new devices might still be required.

[0005]Accordingly, it would be desirable to develop techniques and devices
for UWB WPAN devices which overcome the aforementioned drawbacks.

SUMMARY

[0006]Systems and methods according to the present invention address this
need and others by providing techniques for association between wireless
communication devices.

[0007]According to one exemplary embodiment of the invention, a method for
associating wireless communication devices includes the step of
transmitting and receiving a signal useable to obtain ranging information
between two wireless communication devices. The ranging information is
then used to automatically determine whether the wireless communication
devices are associated with one another. This determination can be based,
for example, on relative changes in position, measured velocity of one
device during a measurement period and/or measured acceleration of one
device during the measurement period.

[0008]According to another exemplary embodiment of the invention, a
wireless communication device has a transceiver capable of transmitting
and receiving a signal from which ranging information can be obtained,
and a processor capable of processing the ranging information to
determine whether an association has occurred between two wireless
communication devices.

[0012]FIG. 2 depicts an exemplary method for two UWB devices to range one
another.

[0013]FIG. 3 shows a gesture used to initiate association according to an
exemplary embodiment of the present invention.

[0014]FIG. 4(a) illustrates association criteria based on distance versus
time according to an exemplary embodiment of the present invention.

[0015]FIG. 4(b) illustrates association criteria based on speed versus
time according to an exemplary embodiment of the present invention.

[0016]FIG. 4(c) illustrates association criteria based on acceleration
versus time according to an exemplary embodiment of the present
invention.

[0017]FIG. 5 depicts an exemplary method of UWB device association
according to an exemplary embodiment of the present invention.

[0018]FIG. 6 shows how a UWB device discriminates between PNCs according
to an exemplary embodiment of the present invention.

[0019]The following detailed description of the invention refers to the
accompanying drawings. The same reference numbers in different drawings
identify the same or similar elements. Also, the following detailed
description does not limit the invention. Instead, the scope of the
invention is defined by the appended claims.

[0020]In order to provide some context for this description, exemplary UWB
WPAN systems in which exemplary embodiments of the present invention can
be implemented will now be described with respect to FIG. 1(a) and FIG.
1(b). FIG. 1(a) shows a UWB WPAN of just two devices, i.e., a PNC 10 and
another UWB device 12, such as a PDA. The UWB devices each include a
transceiver and processor, e.g., the transceiver 14 and processor 16 of
PDA device 12, for wirelessly communicating with one another and
processing information as described below. FIG. 1(b) shows a UWB WPAN
consisting of multiple devices in a piconet which communicate with each
other, such as a PC 20, a printer 22, a cell phone 24, and a digital
camera 26. These devices communicate using UWB communication techniques,
however the present invention is not limited to wireless communication
devices which use UWB techniques. As will be appreciated by those skilled
in the art, UWB communication techniques provide for high data rate and
low power output communications, using a variety of modulation techniques
over a very large bandwidth. More details regarding UWB communication
techniques are available in the draft specification from IEEE task group
802.15.3a.

[0021]One aspect of UWB devices of interest for this specification is
their capability to implement ranging functions due to the very large
bandwidth associated with the signals that they transmit. It is
anticipated that these ranging functions will be able to provide ranging
information which identifies a distance between, e.g. PNC 10 and PDA 12,
to within a predetermined precision, e.g. 10 cm. This ranging information
can be used according to exemplary embodiments of the present invention
to provide an automated association between UWB devices.

[0022]An exemplary ranging function which can be implemented between the
UWB devices of FIG. 1(a), will now be described with respect to the
flowchart of FIG. 2. According to exemplary embodiments of the present
invention, a two-way time transfer (TWTT) technique can be used to
perform ranging between any two UWB devices. Two messages (A and B) are
exchanged between the devices 10 and 12 at step 200. The two messages can
be transmitted simultaneously by the two devices or one message can be
transmitted first and the second message transmitted by the second UWB
device upon receipt of the first message. In either case, the
transmission time (Ta and Tb) and the reception time (Ra and Rb) of both
messages are recorded at step 210. The two UWB devices 10 and 12 will be
separated by an unknown distance (unknown propagation delay,
tpropagation) and will have an unknown offset between their internal
clocks (toffset). These two unknowns can be solved for by setting up two
simultaneous equations in two unknowns as:

Ra=Ta+toffset+tpropagation (1)

Rb=Tb-toffset+tpropagation (2)

[0023]and then solving for toffset and tpropagation at step 220. The range
between the devices 10 and 12 can then be determined directly from the
propagation delay and the known speed of the transmissions at step 240.
It will be appreciated that the foregoing is simply an example of one
ranging technique which can be used in techniques according to the
present invention and that other ranging techniques may be substituted
therefor.

[0024]According to exemplary embodiments of the present invention, the
ranging information obtained using, for example, the techniques described
above, can be used to automatically determine if UWB devices become
associated (or disassociated) with one another. Changes in relative
positions between two UWB devices can be, for example, detected and
compared to predetermined conditions to determine if an association (or
disassociation) occurs. FIG. 3 shows an example of two UWB devices which
a user intends to associate with one another. Therein, one UWB device 30
is stationary and the other UWB device 32 is moved by a user to close the
distance between the two UWB devices. From positional data obtained
during a measurement period, this movement can be identified as an
association gesture. Note, however, that the present invention is not to
be considered limited to embodiments where one device is stationary and
one device is mobile. The present invention includes motion by either or
both devices, as well as applications where multiple devices are
associating with one another.

[0025]According to an exemplary embodiment of the present invention,
association can be determined through various types of positional data.
The associating gesture described above (or other gestures) can be
defined by certain parameters which can, in turn, be derived from ranging
information. For example one or more of: (1) distance between the devices
at time t1 (start of measurement time) and time t2 (end of measurement
time), (2) speed of device movement at time t1 and time t2, and (3)
acceleration of the device at time t1 and time t2, can be used to define
and identify the occurrence of an associating gesture. FIG. 4(a)
illustrates an exemplary distance parameter. For example, if the distance
between devices 30 and 32 closes by more than a predetermined amount
(e.g., 15 cm) during the measurement period (e.g., one second), then the
movement can be identified as an associating gesture. Similarly, if the
velocity is near zero, increases, then returns to zero during the
measurement period, then this may also be identified as indicative of an
associating gesture as shown in FIG. 4(b). Likewise, for an associating
gesture involving a user "poking" a portable UWB device toward another
UWB device, the acceleration should first be positive, and then negative
for some portion of the measurement period. Thresholds also can be
applied to the velocity and/or acceleration tests. The tests can be used
individually, alternatively (logical OR) or together (logical AND). Thus,
according to one exemplary embodiment of the present invention, an
association will be identified by device 30 or 32 as occurring when (a)
the distance between the two devices decreases by a predetermined amount
during the measurement period, (b) the velocity goes from zero to a
positive velocity and back to zero during the measurement period, and (c)
the acceleration is first positive and then negative during the
measurement period.

[0026]According to an exemplary embodiment of the present invention, a
method for associating devices using the above-described associating
gesture operates as illustrated in the flowchart of FIG. 5. Relative
positional information is determined between UWB device 30 and UWB device
32 at time t1 (step 502). A closing gesture occurs, moving one UWB device
closer to another UWB device (step 504). Ranging information is gathered
on an ongoing basis between devices 30 and 32. At time t2, the
measurement period ends (step 506). At this point all of the relative
positional information gathered between time t1 and time t2 is processed
(step 508) to determine if association between the devices occurred
during the measurement period. In this example, an absolute distance
threshold is first employed so that only gestures performed proximate
another device are identified as associating gestures, i.e., only devices
which are physically close together can become associated with one
another even if a more distant device could detect the associating
gesture. Thus, if the UWB devices are within a specified minimum distance
(e.g., one meter) then association is permitted at step 510, if not then
association does not occur (step 511). If the change in relative distance
between the UWB devices exceeds the minimum threshold during the
measurement period then association could occur, if not then association
does not occur (step 512). If the gesturing device is at the correct
speed at time t1 and time t2 then association could occur, if not then
association does not occur (step 514). If the gesturing device shows the
correct acceleration characteristics during the time period from time t1
to time t2 then association could occur, if not then association does not
occur (step 516). If all four positional conditions were met during the
processing illustrated in FIG. 5 then association occurs (step 518).

[0027]According to an exemplary embodiment of the current invention, the
foregoing embodiments can be combined with other tests, e.g., the
aforedescribed user-gated techniques. For example, these ranging
association techniques can be used in conjunction with one or more of:
(1) providing each UWB device with a printed card having a serial number.
This serial number is entered into a PC (for example) that the user
wishes to be able to associate with the UWB device and then, when the UWB
device gets in range of the PC, a YES/NO dialog box is displayed for
confirmation of the association; (2) providing both the PNC and UWB
device with "associate now" buttons that are pressed simultaneously to
establish an association; (3) to use an intra-red transmission to
initiate the request for association and transfer other information as
required; (4) other user-gated authorization techniques. According to an
exemplary embodiment of the current invention, any or all of the above
user-gated authorization techniques could be used in conjunction with any
of the ranging information described above to provide a robust technique
for ensuring that a device is allowed to associate when a new device is
detected by the PNC.

[0028]UWB devices that have become associated with one another will have
the ability to leave the piconet or disassociate. According to an
exemplary embodiment of the current invention, disassociation between UWB
devices, for example device 30 and device 32, occurs when the
predetermined action(s) related to association is repeated, when an
action that is the reverse of the associating gesture occurs, or based on
a condition that is not either of the above, for example, powering off a
UWB device.

[0029]In some environments, an associating gesture may be performed by a
user with a handheld UWB proximate a number of candidates for
association. One way to determine the device with which the user wishes
to establish an association is to use previous association data, e.g., to
assume that the user wants to associate with the same device with which a
previous association was established. Of course, the same handheld device
may have previously been associated with a number of nearby devices.
Thus, according to another exemplary embodiment of the present invention,
using the relative positional data previously acquired via the ranging
techniques, a voting procedure among PNCs could be used, whereby, the PNC
with which the user's device experiences the largest relative amplitude
change for one or more of distance, speed, and acceleration is the device
that is identified for association. This operates relative to the user's
device 60 on the principle that a scaling factor cos applies to these
measurements, when observed by a PNC at an angle of to the axis of the
pointing gesture. This can be seen in FIG. 6, wherein the relative angles
of 1, 2, 3 will affect the relative measurements associated with changes
in distance, velocity and/or acceleration relative to PNC 1, PNC 2 and
PNC 3.

[0030]According to another exemplary embodiment of the current invention,
when a UWB device becomes associated or disassociated from another UWB
device user feedback is provided. This user feedback, for example, could
be in the form of a synthesized sound similar to the click of a
mechanical plug being inserted and could be generated from either or both
UWB devices. Other sounds or forms of media, such as a light, could be
used to provide user feedback on association or disassociation of UWB
devices.

[0031]The above-described exemplary embodiments are intended to be
illustrative in all respects, rather than restrictive, of the present
invention. Thus the present invention is capable of many variations in
detailed implementation that can be derived from the description
contained herein by a person skilled in the art. All such variations and
modifications are considered to be within the scope and spirit of the
present invention as defined by the following claims. No element, act, or
instruction used in the description of the present application should be
construed as critical or essential to the invention unless explicitly
described as such. Also, as used herein, the article "a" is intended to
include one or more items.